Fast radio bursts as electromagnetic radiation from cusps on superconducting cosmic strings

Abstract

Cosmic strings are topological defects, relicts of the early Universe, which can be formed during phase transitions of fields with spontaneous broken symmetry. There also exists a special class of cosmic strings - superconducting cosmic strings, inside of which the massless charge carriers, so-called zero modes, are presented and can move along the string without any resistance. The superconducting cosmic strings during their relativistic motion through the cosmic plasma could be a powerful source of electromagnetic radiation. The emission of cusps on the superconducting strings is highly beamed and has the nature of bursts. In the present work, it is shown, that the millisecond extragalactic radio bursts, discovered during the last decade, called the fast radio bursts (FRB), with unknown nature, could be explained as radiation from cusps on superconducting cosmic strings. Estimates made for ten FRBs discovered till now show that bursts could be produced by a string with α = ΓGµ/c² ∼ 5 · 10⁻¹³ − 10⁻¹², where Γ ∼ 50 is a dimensionless parameter, G is the gravitational constant, c is the speed of light, µ is the mass per unit length of a string, which corresponds to the energy scale of the phase transition η ∼ 1.2 · 10¹² − 1.7 · 10¹² GeV. The observed duration, flux and event rate are in a good agreement with the proposed model. In the framework of emission from cusps of superconducting cosmic string loops, probability of FRB detecting is estimated, which is found to be highly close to the probability of detecting, given by observational data.